The present invention relates to vibratory conveying equipment for moving bulk material, and, more particularly, to a vibratory distribution conveyor that allows for the distribution of conveyed materials at different locations along the length of the conveyor deck.
Vibratory conveyors are well known is the art and are commonly used for moving bulk materials. One type of common vibratory conveyor is a brute force conveyor, in which a force is imparted to the material-carrying deck at an angle relative to horizontal plane defined by the deck so that the material moves with the deck along this angle. Once the force is reversed, the deck moves in the reverse direction, allowing the material to fall to the deck in a more forward position. An eccentric shaft drive system is generally used to impart the requisite cyclical force to the deck, which is mounted to a stationary support through a plurality of elastic members such as springs. The eccentric shaft drive system comprises one or more rotating shafts and associated weights so as to impart the cyclical resultant force to the vibratory deck. In simple terms, the conveyed material is essentially xe2x80x9cbouncedxe2x80x9d along the deck from an inlet end to a discharge end. Thus, through much of its travel, the conveyed material is airborne, and the material actually contacts the deck only long enough to be re-launched into the air in the direction of the.discharge end of the deck.
In any event, there are some applications in which it would be preferable to distribute the conveyed material at different locations along the length of the conveyor deck, rather than solely at the discharge end. For example, U.S. Pat. No. 6,112,883 issued to Kraus, et al. and assigned to General Kinematics of Barrington, Ill. describes a vibratory distribution conveyor that includes a means for controlling declination of the deck about an axis extending from the inlet end to the discharge end so as to distribute conveyed materials over the side or distribution edge of the deck 22. Specifically, there is a pivotable connection between the planar conveying surface of the deck and a frame member disposed below the deck to accommodate pivoting movement of the deck about the longitudinal axis extending from the inlet end to the discharge end. As for the declination controlling means, an inflatable and deflatable bag is positioned below the deck on the side opposite of a distribution edge to control the angle of declination of the deck relative to the longitudinal axis. By controlling the inflation and deflation of the bag, the deck can be oriented to cause materials to conveyed, under the force of gravity, off of the deck along the distribution edge.
However, such a construction of a vibratory distribution conveyor is substantially complex, requiring not only an appropriate control system for the eccentric shaft drive system, but also requiring a control system for the declination equipment. Furthermore, air bellows or inflatable bags and rubber torsion springs are subject to rapid wear and require frequent maintenance.
It is therefore a paramount object of the present invention to provide a vibratory distribution conveyor that allows for the distribution of conveyed material at different locations along the length of the conveyor deck, rather than solely at the discharge end, but without the inherent mechanical and control complexities associated with manipulating the declination of the conveyor deck.
This and other objects and advantages of the present invention will become apparent upon a review of the following description and appended claims.
The present invention is a vibratory conveyor that allows for the distribution of conveyed material at different locations along the length of the conveyor deck, rather than solely at the discharge end, but without the necessity of controlling declination of the conveyor deck.
A preferred vibratory conveyor made in accordance with the present invention has a frame that is mounted to a stationary base by a plurality of isolating springs. The frame of the vibratory conveyor comprises a lower housing and an upper deck. The lower housing is mounted to the stationary base and encloses an eccentric weight drive system. The upper deck is a generally horizontal conveying surface that is secured to the lower housing.
The preferred eccentric shaft drive system includes a pair of counter-rotating drive shafts, each such shaft carrying eccentric weights. The first and second drive shafts are interposed between and rotatably mounted to inner support walls of the lower housing and supported by respective bearings, such that the eccentric shaft drive system is mounted at an angle relative to horizontal plane defined by the conveyor deck. Each drive shaft is independently driven by a motor through a belt and pulley arrangement. Rotation of the drive shafts and associated eccentric weight elements causes a net force to be imparted to the conveyor deck at an angle relative to horizontal plane defined by the deck to convey material forward. However, the drive shafts are mounted and controlled such that changing the phase angle between the respective drive shafts causes a change in direction of the net force output of the drive system, thereby resulting in a directional or sideways conveying motion.
To accomplish the requisite control of the phase angle relationship between the respective drive shafts, a sensor or proximity switch is located adjacent each of the drive shafts for sensing the position of each shaft. Signals representing the respective positions of the drive shafts are then provided to a controller, which, in response to the time sequence or value thereof, generates a real-time phase angle signal corresponding to the relative phase angle difference between the two drive shafts. The controller then compares the value of the real-time phase angle signal to a predetermined phase angle signal representing the desired direction of the resultant force. The controller then provides a signal to a variable frequency drive to cause it to continuously adjust the speed of one or both of the motors until the real-time phase angle signal approximates the predetermined, programmed value. Through control of the motors in this manner, the phase angle between the respective drive shafts can be changed, thereby causing a change in direction of the net force output of the drive system, and resulting in a directional or sideways conveying motion. Distribution of conveyed material at different locations along the length of the conveyor deck is therefore possible without the necessity of controlling declination of the conveyor deck.